This invention is generally directed to germanium phthalocyanines and processes for the preparation thereof and, more specifically, the present invention is directed to processes for the preparation of dihydroxygermanium phthalocyanine. In embodiments, the process of the present invention comprises the formation of a novel polymorph of dihydroxygermanium phthalocyanine, which is herein referred to as Type III dihydroxygermanium phthalocyanine. This polymorph can be obtained, for example, by acid hydrolysis of dihalogermanium phthalocyanine or dialkoxygermanium phthalocyanine, followed by treatment with an organic base such as tertiary amine, and washing with aprotic organic solvent such as alcohol. Alternatively, the Type III dihydroxygermanium phthalocyanine can also be prepared by polymorphic conversion of other polymorphs of dihydroxygermanium phthalocyanine by appropriate physical or chemical treatment. For example, Type III dihydroxygermanium phthalocyanine can be converted to Type III polymorph by stirring Type I in a mixed solvent medium of trifluoroacetic acid and methanol, while Type II polymorph provides Type III polymorph when treated with methanol. Type III dihydroxygermanium phthalocyanine can be selected as organic photogenerator pigments in layered photoresponsive imaging members with charge transport layers, such as infrared light responsive pigments, especially hole transport layers containing hole transport molecules such as known tertiary aryl amines. The aforementioned photoresponsive imaging members can be negatively charged when the photogenerating layer is situated between the hole transport layer and the substrate, or positively charged when the hole transport layer is situated between the photogenerating layer and the supporting substrate. The layered photoconductive imaging members can be selected for a number of different known imaging and printing processes including, for example, electrophotographic imaging processes, especially xerographic imaging and printing processes wherein negatively charged or positively charged images are rendered visible using toner compositions of appropriate charge polarity. In general, the imaging members are sensitive in the wavelength regions of from about 550 to about 800 nanometers, thus diode lasers can be selected as the light source.
Dihydroxygermanium phthalocyanine is a known infrared photoresponsive photogenerator pigment, and can be prepared from dichlorogermanium phthalocyanine by treatment with concentrated sulfuric acid followed by hydrolysis and washing with water or aqueous base as disclosed, for example, in U.S. Pat. No. 4,557,989, the disclosure of which is totally incorporated herein by reference. The resulting dihydroxygermanium phthalocyanine has been shown to exhibit a crystalline polymorph (herein referred to as Type I) whose solid state absorption spectrum extends from about 500 to over 1,000 nanometers. Layered photoresponsive imaging members using Type I dihydroxygermanium phthalocyanine generally exhibit high photosensitivities in the 600 to 900 nanometers spectral region, however, the dark decay thereof is generally high. Dark decay values of over 100 volts per second are typical of these imaging members. Photoresponsive imaging members with Type III dihydroxygermanium phthalocyanine photogenerator pigment as prepared with the processes of the present invention have substantially improved characteristics such as lower dark decay, higher photosensitivity, better cyclic stability, and the like as illustrated herein.
In Konica Japanese 64-17066/89, there is disclosed, for example, the use of a new crystal modification of titanyl phthalocyanine (TiOPc) prepared from alpha-type titanyl phthalocyanine (Type II) by milling it in a sand mill with salt and polyethylene glycol. This publication also discloses that this new polymorph differs from alpha-type pigment in its light absorption and shows a maximum absorbance at 817 nanometers while the alpha-type exhibits a maximum at 830 nanometers. The Konica publication also discloses the use of this new form of TiOPc in a layered electrophotographic device having high photosensitivity at an exposure radiation of 780 nanometers. Further, this new polymorph of TiOPc is also described in U.S. Pat. No. 4,898,799 and in a paper presented at the Annual Conference of Japan Hardcopy in July 1989. In this paper, this same new polymorph is referred to as Type Y, and reference is also made to Types I, II, and III as A, B, and C, respectively.
Layered photoresponsive imaging members have been described in a number of U.S. patents, such as U.S. Pat. No. 4,265,900, the disclosure of which is totally incorporated herein by reference, wherein there is illustrated an imaging member comprised of a photogenerating layer, and an aryl amine hole transport layer. Examples of photogenerating layer components include trigonal selenium, metal phthalocyanines, vanadyl phthalocyanines, and metal free phthalocyanines. Additionally, there is described in U.S. Pat. No. 3,121,006 a composite xerographic photoconductive member comprised of finely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. The binder materials disclosed in the '006 patent comprise a material which is substantially incapable of transporting for any significant distance injected charge carriers generated by the photoconductive particles.
The use of certain perylene pigments as photoconductive substances is also known. There is thus described in Hoechst European Patent Publication 0040402, DE3019326, filed May 21, 1980, the use of N,N'-disubstituted perylene-3,4,9,10-tetracarboxyldiimide pigments as photoconductive substances. Specifically, there is, for example, disclosed in this publication N,N'-bis(3-methoxypropyl)perylene-3,4,9, 10-tetracarboxyldiimide dual layered negatively charged photoreceptors with improved spectral response in the wavelength region of 400 to 700 nanometers. A similar disclosure is revealed in Ernst Gunther Schlosser, Journal of Applied Photographic Engineering, Vol. 4, No. 3, page 118 (1978). There are also disclosed in U.S. Pat. No. 3,871,882 photoconductive substances comprised of specific perylene-3,4,9,10-tetracarboxylic acid derivative dyestuffs. In accordance with the teachings of this patent, the photoconductive layer is preferably formed by vapor depositing the dyestuff in a vacuum. Also, there is specifically disclosed in this patent dual layer photoreceptors with perylene-3,4,9,10-tetracarboxylic acid diimide derivatives, which have spectral response in the wavelength region of from 400 to 600 nanometers. Also, in U.S. Pat. No. 4,555,463, the disclosure of which is totally incorporated herein by reference, there is illustrated a layered imaging member with a chloroindium phthalocyanine photogenerating layer. In U.S. Pat. No. 4,587,189, the disclosure of which is totally incorporated herein by reference, there is illustrated a layered imaging member with a perylene pigment photogenerating component. Both of the aforementioned patents disclose an aryl amine component as a hole transport layer.
In copending application U.S. Ser. No. 537,714, the disclosure of which is totally incorporated herein by reference, there are illustrated photoresponsive imaging members with photogenerating titanyl phthalocyanine layers prepared by vacuum deposition. It is indicated in this copending application that the imaging members comprised of the vacuum deposited titanyl phthalocyanines and aryl amine hole transporting compounds exhibit superior xerographic performance with low dark decay characteristics and high photosensitivity, particularly in comparison to several prior art imaging members prepared by solution coating or spray coating, reference for example, U.S. Pat. No. 4,429,029 mentioned hereinbefore.
In U.S. Pat. No. 5,153,313, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of phthalocyanine composites which comprises adding a metal-free phthalocyanine, a metal phthalocyanine, a metalloxy phthalocyanine or mixtures thereof to a solution of trifluoroacetic acid and a monohaloalkane; adding to the resulting mixture a titanyl phthalocyanine; adding the resulting solution to a mixture that will enable precipitation of said composite; and recovering the phthalocyanine composite precipitated product.
In U.S. Pat. No. 5,166,339, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of titanyl phthalocyanine which comprises the reaction of titanium tetrapropoxide with diiminoisoindolene in N-methylpyrrolidone solvent to provide Type I, or .beta.-type titanyl phthalocyanine as determined by X-ray powder diffraction analysis; dissolving the resulting titanyl phthalocyanine in a mixture of trifluoroacetic acid and methylene chloride; adding the resulting mixture to a stirred organic solvent, such as methanol, or to water; separating the resulting precipitate by, for example, vacuum filtration through a glass fiber paper in a Buchner funnel; and washing the titanyl phthalocyanine product. Examples of titanyl phthalocyanine reactants that can be selected in effective amounts of, for example, from about 1 weight percent to about 40 percent by weight of the trifluoroacetic acidic solvent mixture include known available titanyl phthalocyanines; titanyl phthalocyanines synthesized from the reaction of titanium halides such as titanium trichloride, titanium tetrachloride or tetrabromide, titanium tetraalkoxides such as titanium tetra-methoxide, -ethoxide, -propoxide, -butoxide, oisopropoxide and the like; and other titanium salts with compounds such as phthalonitrile and diiminoisoindolene in solvents such as 1-chloronaphthalene, quinoline, N-methylpyrrolidone, and alkylbenzenes such as xylene at temperatures of from about 120 to about 300.degree. C; specific polymorphs of titanyl phthalocyanine such as Type I, II, III, and IV, the preparation of which, for example, is described in the literature; or any other suitable polymorphic form of TiOPc; substituted titanyl phthalocyanine pigments having from 1 to 16 substituents attached to the outer ring of the compound, said substituent being, for example, halogens such as chloro-, bromo-, iodo- and fluoro-, alkyls with from 1 to about 6 carbon atoms such as methyl-, ethyl-, propyl-, isopropyl-, butyl-, pentyl-, and hexyl-; nitro, amino, alkoxy and alkylthio, such as methoxy-, ethoxy- and propylthio- groups; and mixtures thereof.
Disclosed in U.S. Pat. No. 5,164,493 is a process for the preparation of titanyl phthalocyanine Type I which comprises the addition of titanium tetraalkoxide in a solvent to a mixture of phthalonitrile and a diiminoisoindolene, followed by heating. The disclosure of this patent is totally incorporated herein by reference. Disclosed in U.S. Pat. 5,189,156 is a process for the preparation of titanyl phthalocyanine Type I which comprises the reaction of titanium tetraalkoxide and diiminoisoindolene in the presence of a halonaphthalene solvent; and disclosed in U.S. Pat. No. 5,206,359 is a process for the preparation of titanyl phthalocyanine which comprises the treatment of titanyl phthalocyanine Type X with a halobenzene, the disclosures of which are totally incorporated herein by reference.
In U.S. Pat. No. 5,407,766 and copending application U.S. Ser. No. 169,486, the disclosures of which are totally incorporated herein by references, there is illustrated a process for the preparation of hydroxygallium phthalocyanine which comprises the synthesis of a precursor halogallium phthalocyanine by the reaction of a diiminoisoindolene with gallium acetylacetonate; hydrolysis thereof to hydroxygallium phthalocyanine; and conversion of the resulting hydroxygallium phthalocyanine obtained to Type V hydroxygallium phthalocyanine by contacting said resulting hydroxygallium phthalocyanine with an organic solvent; and a process for the preparation of hydroxygallium phthalocyanine which comprises hydrolysis of halogallium phthalocyanine precursor to a hydroxygallium phthalocyanine, and conversion of said resulting hydroxygallium phthalocyanine to Type V hydroxygallium phthalocyanine by contacting said resulting hydroxygallium phthalocyanine with an organic solvent; and wherein said precursor halogallium phthalocyanine is obtained by the reaction of gallium halide with diiminoisoindolene in an organic solvent.
The disclosures of all of the aforementioned publications, laid open applications, copending applications and patents are totally incorporated herein by reference.